My portraits are recognized and remembered for a couple of reasons. one of these is the suppleness and believability of skin depth and texture. it is important to get references with subtle shadows. Even if you have these in your references and even if you paint them solidly into your grasaille or underpainting, the difficult part is understanding how to finesse the light and dark to enhance the value and increase the three dimensionality of the flesh. I tell my students to remember that shadowed flesh must still have skin, I have heard other artists teach not to add white into the shadows. Practice seeing and applying transparent amounts of skin over the shadows, especially on babies and elderly subjects. Look carefully at the shadowed areas where I have laid in the skin. Later observe how obscure but realistic it looks. Keep in mind the many layers it takes to achieve this look. Enjoy, Diana